pgsql: doc: change pg_upgrade wal_level to be not minimal

doc: change pg_upgrade wal_level to be not minimal

Previously it was specified to be only replica.

Discussion: /messages/by-id/20200618180058.GK7349@momjian.us

Backpatch-through: 9.5

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/1c76a141f32918dff4e1f552535f96b2dc7af0a8

Modified Files
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doc/src/sgml/ref/pgupgrade.sgml | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)